Polymerisation catalysts

ABSTRACT

A catalyst for the polymerisation of 1-olefins is disclosed, which comprises (1) a compound of Formula B wherein M is Fe[II], Fe[III], Co[I], Co[II], Co[III], Mn[I], Mn[II], Mn[III], Mn[IV], Ru[II], Ru[III] or Ru[IV]; X represents an atom or group covalently or ionically bonded to the transition metal M; T is the oxidation state of the transition metal M and b is the valency of the atom or group X; R 1 , R 2 , R 3 , R 4 , R 5 , R 6  and R 7  are independently selected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl; and when any two or more of R 1 -R 7  are hydrocarbyl, substituted hydrocarbyl, htctrohydrocarbyl or substituted heterohydrocarbyl, said two or more can be linked to form one or more cyclic substituents; and (2) a further catalyst. Copolymers made using the catalyst having specific physical properties are also disclosed.

[0001] The present invention relates to novel transition metal compoundsand to their use as polymerisation catalysts.

[0002] The use of certain transition metal compounds to polymerise1-olefins, for example, ethylene, is well established in the prior art.The use of Ziegler-Natta catalysts, for example, those catalystsproduced by activating titanium halides with organometallic compoundssuch as triethylaluminium, is fundamental to many commercial processesfor manufacturing polyolefins. Over the last twenty or thirty years,advances in the technology have led to the development of Ziegler-Nattacatalysts which have such high activities that that olefin polymers andcopolymers containing very low concentrations of residual catalyst canbe produced directly in commercial polymerisation processes. Thequantities of residual catalyst remaining in the produced polymer are sosmall as to render unnecessary their separation and removal for mostcommercial applications. Such processes can be operated by polymerisingthe monomers in the gas phase, or in solution or in suspension in aliquid hydrocarbon diluent. Polymerisation of the monomers can becarried out in the gas phase (the “gas phase process”), for example byfluidising under polymerisation conditions a bed comprising the targetpolyolefin powder and particles of the desired catalyst using afluidising gas stream comprising the gaseous monomer. In the so-called“solution process” the (co)polymerisation is conducted by introducingthe monomer into a solution or suspension of the catalyst in a liquidhydrocarbon diluent under conditions of temperature and pressure suchthat the produced polyolefin forms as a solution in the hydrocarbondiluent. In the “slurry process” the temperature, pressure and choice ofdiluent are such that the produced polymer forms as a suspension in theliquid hydrocarbon diluent. These processes are generally operated atrelatively low pressures (for example 10-50 bar) and low temperature(for example 50 to 150° C.).

[0003] Commodity polyethylenes are commercially produced in a variety ofdifferent types and grades. Homopolymerisation of ethylene withtransition metal based catalysts leads to the production of so-called“high density” grades of polyethylene. These polymers have relativelyhigh stiffness and are useful for making articles where inherentrigidity is required. Copolymerisation of ethylene with higher 1-olefins(e.g. butene, hexene or octene) is employed commercially to provide awide variety of copolymers differing in density and in other importantphysical properties. Particularly important copolymers made bycopolymerising ethylene with higher 1-olefins using transition metalbased catalysts are the copolymers having a density in the range of 0.91to 0.93. These copolymers which are generally referred to in the art as“linear low density polyethylene” are in many respects similar to the socalled “low density” polyethylene produced by the high pressure freeradical catalysed polymerisation of ethylene. Such polymers andcopolymers are used extensively in the manufacture of flexible blownfilm.

[0004] An important feature of the microstructure of the copolymers ofethylene and higher 1-olefins is the manner in which polymerisedcomonomer units are distributed along the “backbone” chain ofpolymerised ethylene units. The conventional Ziegler-Natta catalystshave tended to produce copolymers wherein the polymerised comonomerunits are clumped together along the chain. To achieve especiallydesirable film properties from such copolymers the comonomer units ineach copolymer molecule are preferably not clumped together, but arewell spaced along the length of each linear polyethylene chain. Inrecent years the use of certain metallocene catalysts (for examplebiscyclopentadienylzirconiumdichloride activated with alumoxane) hasprovided catalysts with potentially high activity and capable ofproviding an improved distribution of the comonomer units. However,metallocene catalysts of this type suffer from a number ofdisadvantages, for example, high sensitivity to impurities when usedwith commercially available monomers, diluents and process gas streams,the need to use large quantities of expensive alumoxanes to achieve highactivity, and difficulties in putting the catalyst on to a suitablesupport.

[0005] WO98/27124, published after the earliest priority date of thisinvention, discloses that ethylene may be polymerised by contacting itwith certain iron or cobalt complexes of selected2,6-pyridinecarboxaldehydebis(imines) and 2,6-diacylpyridinebisoimines);and our own copending application GB 9718775.1 has disclosedpolymerisation catalysts containing novel nitrogen-containing transitionmetal compounds which comprise the skeletal unit depicted in Formula B:

[0006] wherein M is Fe[II], Fe[II], Co[I], Co[II], Co[III], Mn[I],Mn[II], Mn[III], Mn[IV], Ru[II], Ru[III] or Ru[IV]; X represents an atomor group covalently or ionically bonded to the transition metal M; T isthe oxidation state of the transition metal M and b is the valency ofthe atom or group X; R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are independentlyselected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl; and when any two ormore of R¹-R⁷ are hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl, said two or more canbe linked to form one or more cyclic substituents.

[0007] An object of the present invention is to provide a novel catalystsystem suitable for polymerising monomers, for example, olefins, andespecially for polymerising ethylene alone or for copolymerisingethylene with higher 1-olefins. A further object of the invention is toprovide an improved process for the polymerisation of olefins,especially of ethylene alone or the copolymerisation of ethylene withhigher 1-olefins to provide homopolymers and copolymers havingcontrollable molecular weights. We have unexpectedly discovered that thecombination of catalysts of the Formula B with other catalysts canproduce a highly active catalytic system in which the resultant polymersexhibit improved performance and processing properties.

[0008] The present invention provides a polymerisation catalystcomprising

[0009] (1) a compound of the Formula B:

[0010] wherein M is Fe[II], Fe[III], Co[I], Co[II], Co[III], Mn[I],Mn[II], Mn[III], Mn[IV], Ru[II], Ru[III] or Ru[IV]; X represents an atomor group covalently or ionically bonded to the transition metal M; T isthe oxidation state of the transition metal M and b is the valency ofthe atom or group X; R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are independentlyselected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl; and when any two ormore of R¹-R⁷ are hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl, said two or more canbe linked to form one or more cyclic substituents; and

[0011] (2) a further catalyst.

[0012] The catalysts (1) and (2) can if desired both be a transitionmetal compound of Formula B. The catalyst may comprise, for example, amixture of 2,6-diacetylpyridinebis(2,6-diisopropylanil)FeCl₂ complex and2,6-diacetylpyridinebis(2,4,6-trimethylanil)FeCl₂ complex, or a mixtureof 2,6-diacetylpyridine(2,6-disopropylanil)CoCl₂ and2,6-diacetylpyridinebis(2,4,6-trimethylanil)FeCl₂. However preferablythe further catalyst (2) is not covered by the definition of (1).

[0013] The further catalyst (2) may be for example, a Ziegler Nattacatalyst, a Phillips type (chromium oxide) catalyst or a metallocenecatalyst. Other catalysts (2) include monocyclopentadienyl constrainedgeometry type catalysts and bidentate α-diimine late transition metalcatalysts. Metallocenes may typically be represented by the generalformula:

(C₅R_(n))_(y)Z_(x)(C₅R_(m))ML_((4-y-1))

[0014] where (C₅R_(n)), and (C₅R_(m)) are cyclopentadienyl ligands,

[0015] R is hydrogen, alkyl, aryl, alkenyl, etc.

[0016] M is a Group IVA metal

[0017] Z is a bridging group,

[0018] L is an anionic ligand, and

[0019] y is 0, 1 or 2, n and mare 1-5, x is 0 or 1.

[0020] The most preferred complexes are those wherein y is 1 and L ishalide or alkyl. Typical examples of such complexes arebis(cyclopentadienyl)zirconium dichloride and bis(cyclopentadienylzirconium dimethyl. In such metallocene complexes the cyclopentadienylligands may suitably be substituted by alkyl groups such as methyl,n-butyl or vinyl. Alternatively the R groups may be joined together toform a ring substituent, for example indenyl or fluorenyl. Thecyclopentadienyl ligands may be the same or different. Typical examplesof such complexes are bis(n-butylcyclopentadienyl) zirconium dichlorideor bis (methylcyclopentadienyl)zirconium dichloride.

[0021] Examples of monocyclopentadienyl- or constrained geometrycomplexes may be found in EP 416815A, EP 420436A, EP 418044A and EP491842A the disclosures of which are incorporated herein by reference. Atypical example of such a moncyclopentadienyl complex is(tert-butylamido)(tetramethyl cyclopentadienyl) dimethyl silanetitaniumdimethyl.

[0022] Further examples of metallocene complexes are those wherein theanionic ligand represented in the above formula is replaced with a dienemoiety. In such complexes the transition metal may be in the +2 or +4oxidation state and a typical example of this type of complex isethylene bis indenyl zirconium (II) 1,4-diphenyl butadiene. Examples ofsuch complexes may be found in EP 775148A the disclosure of which isincorporated herein by reference.

[0023] Monocyclopentadienyl complexes having diene moieties have alsobeen used for the polymerisation of olefins. Such complexes may beexemplified by (tert-butylamido)(tetramethylcyclopentadienyl)dimethylsilanetitanium (II) penta-1,3-diene. Such complexes aredescribed in EP 705269A the disclosure of which is incorporated hereinby reference.

[0024] Other transition metal complexes which may comprise catalyst (2)above are complexes having hetero ring ligands attached to thetransition metal, for example O, NR or 1 ligands. Such complexes aredisclosed for example in EP 735057A and may be illustrated by indenylzirconium tris(diethylcarbamate).

[0025] The further catalyst (2) preferably comprises a heterogeneouscatalyst or a supported catalyst which provides a support for thecatalyst (1). It is preferred that the catalyst additionallyincorporates (3) an activating quantity of an activator compoundcomprising a Lewis acid capable of activating the catalyst for olefinpolymerisation, preferably an organoaluminium compound or ahydrocarbylboron compound.

[0026] The activator compound for the catalysts of the present inventionis suitably selected from organoaluminium compounds and hydrocarbylboroncompounds. Suitable organoaluminium compounds include trialkyaluminiumcompounds, for example, trimethylaluminium, triethylaluminium,tributylaluminium, tri-n-octylaluminium, ethylaluminium dichloride,diethylaluminium chloride and alumoxanes. Alumoxanes are well known inthe art as typically the oligomeric compounds which can be prepared bythe controlled addition of water to an alkylaluminium compound, forexample trimethylaluminum. Such compounds can be linear, cyclic ormixtures thereof. Commercially available alumoxanes are generallybelieved to be mixtures of linear and cyclic compounds. The cyclicalumoxanes can be represented by the formula [R¹⁶AlO], and the linearalumoxanes by the formula R¹⁷(R¹⁸AlO), wherein s is a number from about2 to 50, and wherein R¹⁶, R¹⁷, and R¹⁸ represent hydrocarbyl groups,preferably C₁ to C₆ alkyl groups, for example methyl, ethyl or butylgroups.

[0027] Examples of suitable hydrocarbylboron compounds aredimethylphenylammoniumtetra(phenyl)borate, trityltetra(phenyl)borate,triphenylboron, dimethylphenylammonium tetra(pentafluorophenyl)borate,sodium tetrakis[(bis-3,5-trifluoromethyl)phenyl]borate,H⁺(OEt₂)[(bis-3,5-trifluoromethyl)phenyl]borate,trityltetra(pentafluorophenyl)borate and tris(pentafluorophenyl)boron.

[0028] In the preparation of the catalysts of the present invention thequantity of activating compound selected from organoaluminium compoundsand hydrocarbylboron compounds to be employed is easily determined bysimple testing, for example, by the preparation of small test sampleswhich can be used to polymerise small quantities of the monomer(s) andthus to determine the activity of the produced catalyst. It is generallyfound that the quantity employed is sufficient to provide 0.1 to 20,000atoms, preferably 1 to 2000 atoms of aluminium or boron per Fe, Co, Mnor Ru metal atom in the compound of Formula A In a preferred embodiment,the catalyst (1) is supported on a heterogeneous catalyst as catalyst(2), for example, a magnesium halide supported Ziegler Natta catalyst, aPhillips type (chromium oxide) supported catalyst or a supportedmetallocene catalyst. Formation of the supported catalyst can beachieved for example by treating the transition metal compounds of thepresent invention with alumoxane in a suitable inert diluent, forexample a volatile hydrocarbon, slurrying a particulate support materialwith the product and evaporating the volatile diluent. The quantity ofsupport material employed can vary widely, for example from 100,000 to 1grams per gram of metal present in the transition metal compound. Aparticularly preferred support is a Ziegler Natta catalyst. In a furtheraspect of the present invention compound (1) comprises the skeletal unitdepicted in Formula Z:

[0029] wherein M is Fe[II], Fe[M], Co[I], Co[II], Co[III], Mn[I], Mn[H],Mn[m], Mn[IV], Ru[II], Ru[III] or Ru[IV]; X represents an atom or groupcovalently or ionically bonded to the transition metal M; T is theoxidation state of the transition metal M and b is the valency of theatom or group X; R¹ to R⁴, R⁶ and R¹⁹ to R²⁸ are independently selectedfrom hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl; when any two or moreof R¹ to R⁴, R⁶ and R¹⁹ to R²⁸ are hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl, said two or more canbe linked to form one or more cyclic substituents; with the proviso thatat least one of R¹⁹, R²⁰, R²¹ and R²² is hydrocarbyl, substitutedhydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl whenneither of the ring systems P and Q forms part of a polyaromaticfused-ring system. In this particular aspect of the present invention,in the case that neither of the ring systems P and Q forms part of apolyaromatic ring system, it is preferred that at least one of R¹⁹ andR²⁰, and at least one of R²¹ and R²² is selected from hydrocarbyl,substituted hydrocarbyl, heterohydrocarbyl or substitutedheterohydrocarbyl, and most preferably each of R¹⁹, R²⁰, R²¹ and R²² isselected from hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl orsubstituted heterohydrocarbyl.

[0030] In a further aspect of the present invention compound (1)comprises the skeletal unit depicted in Formula Z:

[0031] wherein M is Fe[II], Fe[III], Co[I], Co[II], Co[III], Mn[I],Mn[II], Mn[III], Mn[IV], Ru[II], Ru[III] or Ru[IV]; X represents an atomor group covalently or ionically bonded to the transition metal M; T isthe oxidation state of the transition metal M and b is the valency ofthe atom or group X; R¹ to R⁴, R⁶ and R¹⁹ to R²⁰ are independentlyselected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl; when any two or moreof R¹ to R⁴, R⁶ and R¹⁹ to R²⁸ are hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl, said two or more canbe linked to form one or more cyclic substituents; with the proviso thatR¹⁹, R²⁰, R²¹ and R²² are hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl when neither of thering systems P and Q forms part of a polyaromatic fused-ring system.

[0032] Subject to the foregoing provisos regarding R¹⁹, R²⁰, R²¹ and R²²in Formula Z, R¹ to R⁴, R⁶ and R¹⁹ to R²′ in the compounds depicted inFormulae B and Z of the present invention are preferably independentlyselected from hydrogen and C, to Cs hydrocarbyl, for example, methyl,ethyl, n-propyl, n-butyl, n-hexyl, and n-octyl. In Formula B, R⁵ and R⁷are preferably independently selected from substituted or unsubstitutedalicyclic, heterocyclic or aromatic groups, for example, phenyl,1-naphthyl, 2-naphthyl, 2-methylphenyl, 2-ethylphenyl,2,6-diisopropylphenyl, 2,3-diisopropylphenyl, 2,4-diisopropylphenyl,2,6-di-n-butylphenyl, 2,6-dimethylphenyl, 2,3-dimethylphenyl,2,4-dimethylphenyl, 2-t-butylphenyl, 2,6-diphenylphenyl,2,4,6-trimethylphenyl, 2,6-trifluoromethylphenyl,4-bromo-2,6-dimethylphenyl, 3,5 dichloro2,6-diethylphenyl, and2,6,bis(2,6-dimethylphenyl)phenyl, cyclohexyl and pyridinyl.

[0033] The ring systems P and Q in Formula Z are preferablyindependently 2,6-hydrocarbylphenyl or fused-ring polyaromatic, forexample, 1-naphthyl, 2-naphthyl, 1-phenanthrenyl and 8-quinolinyl.

[0034] In yet a further aspect of the present invention, compound (1)comprises the skeletal unit depicted in Formula T:

[0035] wherein M is Fe[II], Fe[III], Co[I], Co[II], Co[III], Mn[I],Mn[II], Mn[III], Mn[IV], Ru[II], Ru[III] or Ru[IV]; X represents an atomor group covalently or ionically bonded to the transition metal M; T isthe oxidation state of the transition metal M and b is the valency ofthe atom or group X; R¹ to R⁴, R⁶ and R²⁹ to R³² are independentlyselected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl; when any two or moreof R¹ to R⁴, R⁶ and R² to R³² are hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl, said two or more canbe linked to form one or more cyclic substituents

[0036] In the compound of Formula B of the present invention, M ispreferably Fe[II]. In the compounds of Formula Z or Formula T of thepresent invention, M is preferably Fe[II], Mn[II] or Co[IV].

[0037] Examples of the atom or group X in the compounds of Formula B, Zand T are halide, for example, chloride, bromide; iodide; hydride;hydrocarbyloxide, for example, methoxide, ethoxide, isopropoxide,phenoxide; carboxylate, for example, formate, acetate, benzoate;hydrocarbyl, for example, methyl, ethyl, propyl, butyl, octyl, decyl,phenyl, benzyl; substituted hydrocarbyl; heterohydrocarbyl; tosylate;and triflate. Preferably X is selected from halide, hydride andhydrocarbyl. Chloride is particularly preferred.

[0038] A particularly preferred embodiment of the present inventioncomprises a polymerisation catalyst comprising (1) as the transitionmetal compound, the Formula B or Formula Z or Formula T compound, (2) afurther catalyst (preferably not covered by the definition of (1)), andpreferably also (3) an activating quantity of an activator compoundcomprising a Lewis acid capable of activating the catalyst for olefinpolymerisation, preferably an organoaluminium compound or ahydrocarbylboron compound. When catalyst (2) is a Ziegler-Nattacatalyst, then it is preferred that components (1) and (3) are premixedprior to addition to (2).

[0039] In a further aspect of the present invention the polymerisationcatalyst system additionally comprises (4) a neutral Lewis base.

[0040] In this further aspect of the present invention, the transitionmetal compound is preferably of Formula B, Z or T. The iron and cobaltcompounds are preferred. The preferences in relation to the activatorcompound are the same as expressed above in relation to the catalysts ofthe present invention. Neutral Lewis bases are well known in the art ofZiegler-Natta catalyst polymerisation technology. Examples of classes ofneutral Lewis bases suitably employed in the present invention areunsaturated hydrocarbons, for example, alkenes or alkynes, primary,secondary and tertiary amines, amides, phosphoramides, phosphines,phosphites, ethers, thioethers, nitriles, carbonyl compounds, forexample, esters, ketones, aldehydes, carbon monoxide and carbon dioxide,sulphoxides, sulphones and boroxines. Although 1-olefins are capable ofacting as neutral Lewis bases, for the purposes of the present inventionthey are regarded as monomer or comonomer 1-olefins and not as neutralLewis bases per se. However, alkenes which are internal olefins, forexample, 2-butene and cyclohexene are regarded as neutral Lewis bases inthe present invention. Preferred Lewis bases are tertiary amines andaromatic esters, for example, dimethylaniline, diethylaniline,tributylamine, ethylbenzoate and benzylbenzoate. In this particularaspect of the present invention, components (1), (2), (3) and (4) of thecatalyst system can be brought together simultaneously or in any desiredorder. However, if components (3) and (4) are compounds which interacttogether strongly, for example, form a stable compound together, it ispreferred to bring together either components (1), (2) and (3) orcomponents (1), (2) and (4) in an initial step before introducing thefinal defined component. Preferably components (1), (2) and (4) arecontacted together before component (3) is introduced. The quantities ofcomponents (1), (2) and (3) employed in the preparation of this catalystsystem are suitably as described above in relation to the catalysts ofthe present invention. The quantity of the neutral Lewis Base (component(4)) is preferably such as to provide a ratio of component (1)+(2):component (4) in the range 100:1 to 1:1000, most preferably in the range1:1 to 1:20. Components (1), (2) and (4) of the catalyst system can bebrought together, for example, as the neat materials, as a suspension orsolution of the materials in a suitable diluent or solvent (for examplea liquid hydrocarbon), or, if at least one of the components isvolatile, by utilising the vapour of that component. The components canbe brought together at any desired temperature. Mixing the componentstogether at room temperature is generally satisfactory. Heating tohigher temperatures e.g. up to 120° C. can be carried out if desired,e.g. to achieve better mixing of the components. It is preferred tocarry out the bringing together of components (1), (2) and (4) in aninert atmosphere (eg dry nitrogen) or in vacuo. If it is desired to usethe catalyst on a support material (see below), this can be achieved,for example, by preforming the catalyst system comprising components(1), (2), (3) and (4) and impregnating the support material preferablywith a solution thereof, or by introducing to the support material oneor more of the components simultaneously or sequentially. If desired thesupport material itself can have the properties of a neutral Lewis baseand can be employed as, or in place of, component (4). An example of asupport material having neutral Lewis base properties ispoly(aminostyrene) or a copolymer of styrene and aminostyrene (ievinylaniline). In an alternative preferred embodiment, components (2)and (3) are mixed together prior to the addition of component (1). Thisis particularly preferred when catalyst (2) is itself the support, suchthat catalyst (1) and the activator (3) are added separately to thesupport. In a further alternative catalyst (2) and activator (3) areadded separately to catalyst (1).

[0041] The following are examples of nitrogen-containing transitionmetal complexes (1):

[0042] 2,6-diacetylpyridinebis(2,6-diisopropylanil)FeCl₂

[0043] 2,6-diacetylpyridine(2,6-duisopropylanil)MnCl₂

[0044] 2,6-diacetylpyridine(2,6-diisopropylanil)CoCl₂

[0045] 2,6-diacetylpyridinebis(2-tert.-butylanil)FeCl₂

[0046] 2,6-diacetylpyridinebis(2,3-dimethylanil)FeCl₂

[0047] 2,6-diacetylpyridinebis(2-methylanil)FeCl₂

[0048] 2,6-diacetylpyridinebis(2,4-dimethylanil)FeCl₂

[0049] 2,6-diacetylpyridinebis(2,6-dimethylanil)FeCl₂

[0050] 2,6-diacetylpyridinebis(2,6-dimethylanil)FeCl₂

[0051] 2,6-dialdiminepyridinebis(2,4,6-trimethylanil)FeCl₂

[0052] 2,6-dialdiminepyridinebis(2,6-diethylanil)FeCl₂

[0053] 2,6-dialdiminepyridinebis(2,6-diisopropylanil)FeCl₂

[0054] 2,6-dialdiminepyridinebis(1-naphthil)FeCl₂ and

[0055] 2,6-bis(1,1-diphenylhydrazone)pyridine.FeCl₂.

[0056] The present invention further provides a process for thepolymerisation or copolymerisation of 1-olefins, comprising contactingthe monomeric olefin(s) under polymerisation conditions with apolymerisation catalyst comprising (1) a compound based on the FormulaB, T or Z, and (2) a further catalyst. The further catalyst (2) ispreferably not covered by the above definition (1). In a preferredprocess the catalyst additionally comprises an activating quantity of anactivator compound comprising a Lewis acid capable of activating thecatalyst for olefin polymerisation, preferably an organoaluminiumcompound or a hydrocarbylboron compound. The process of the inventionmay also comprise the additional step of blowing the resultant polymerinto a film.

[0057] The catalysts (1) and (2) may be contacted with the olefin to bepolymerised in the form of a single catalyst system, or they may beadded to the reactor separately.

[0058] The process/catalyst of the invention is especially useful forcopolymerising ethylene with other 1-olefins One disadvantage of thecatalysts disclosed in GB 9718775.1 A, where the only catalyst in thesystem is catalyst (1) as defined in this invention, is that theyproduce copolymers having only a relatively low level of comonomerincorporation for a given level of comonomer in the reaction vessel. Wehave discovered that the catalyst system of the present invention canproduce copolymers having significantly higher levels of comonomerincorporation for the same level of comonomer reactant. Thus in apreferred process for the copolymerisation of ethylene and a further1-olefin, particularly a 1-olefin having 6 or more carbon atoms, thedegree of short chain branching per thousand carbons (SCB) in theresultant copolymer is greater than zero and also equal to or greaterthan 18.18R−0.16 where R is the ratio of partial pressure of further1-olefin to that of ethylene. Preferably the SCB is greater than orequal to 18.18R−0.05, more preferably 18.18R−0.04. A further aspect ofthe invention provides a copolymer of ethylene and a further 1-olefinhaving an SCB of 2.0, preferably 3.0 or greater and comprising residuesof a nitrogen-containing iron complex, wherein the iron concentration isfrom 0.01 to 1000 parts by weight per million parts of copolymer,preferably 0.01 to 10 ppm by weight, for example 0.11 to 1.03 ppm byweight.

[0059] The process of the invention also permits the short chainbranching to be preferentially located in a particular portion of themolecular weight distribution of the copolymer. Thus a further aspect ofthe invention provides a method of selecting the portion of themolecular weight distribution of a copolymer of ethylene and a further1-olefin in which units of said further 1-olefin are located, comprisingcontacting the monomeric olefins under polymerisation conditions with apolymerisation catalyst comprising (1) a compound based on the FormulaB, T or Z, and (2) a further catalyst not covered by the abovedefinition (1). Preferably the 1-olefin has 6 or more carbon atoms. In apreferred method the portion of the molecular weight distribution of thecopolymer in which units of the further 1-olefin are located is withinthe 50% by weight of the copolymer having the highest molecular weight.A further aspect of the invention provides a copolymer of ethylene and afurther 1-olefin, particularly a 1-olefin having 6 or more carbon atoms,comprising residues of a nitrogen-containing iron complex wherein theiron concentration is from 0.01 to 10 parts by weight per million partsof copolymer, and in which at least 50%, preferably at least 60% andmore preferably at least 70% of the short chain branching is locatedwithin the 50% by weight of the copolymer having the highest molecularweight. Generally it is preferred that at least 80% of the short chainbranching is located within the 80% by weight of the copolymer havingthe highest molecular weight.

[0060] Copolymerisation permits the control of physical properties ofthe polymer such as density and environmental stress crack resistance;however it generally results in polymers having reduced modulus(rigidity). High modulus (or rigidity) is necessary for pipe andmoulding products where the ability to support hydrostatic loads isimportant, and in film applications where is reduces the degree of sagand misalignment which can occur during film production or handling. Theuse of the catalyst system of the present invention where theheterogeneous catalyst is a Ziegler-Natta catalyst is capable ofproducing copolymers having a higher modulus for a given comonomercontent than has hitherto been possible, and a better blend of physicalproperties such as those mentioned above.

[0061] Accordingly in a further aspect the present invention provides acopolymer of ethylene and a further 1-olefin wherein the degree of shortchain branching per thousand carbons (SCB) is from 2.0 to 10, and therelationship of modulus in MPa (M) to SCB (B) is defined by the equationM=k−62.5B where k is 820 or greater.

[0062] Whilst many copolymers are known having SCB greater than 2, theparticular combination of high SCB, which, for example, is desirable intough films, and high modulus has not hitherto been achievable. Thepreferred range of SCB is between 2 and 8, though more preferably SCB isgreater than 2.5, and most preferably greater than 3.0. The relationshipbetween modulus and SCB is preferably such that k is 830 or greater,more preferably 840 or greater, and particularly 850 or greater. Apreferred relationship is defined by the equation M=k−65.5B where k is850 or greater, a more preferred one by the equation M=k−67.5B where kis 870 or greater, and a particularly preferred one by the equationM=k−70.5B where k is 90° or greater. Another preferred relationship isdefined by the equation M=k−60B where k is 815 or greater, a morepreferred one by the equation M=k−57.5B where k is 810 or greater, and aparticularly preferred one by the equation M=k−55B where k is 805 orgreater. In FIG. 1 a plot of modulus against SCB is shown, whichdemonstrates the region attainable by the invention but not by knowncopolymers. Points are shown on the graph not only for copolymersaccording to the invention, but also for known copolymers. The regioncovered by the invention is that on or above the diagonal line, andbetween SCB/1000C=2.0 and 10.

[0063] Preferred comonomers are olefins having from 4 to 8 carbons, suchas 1-butene, 1-hexene, 4-methylpentene-1, and octene.

[0064] The above copolymers are generally preferred to have highmolecular weights for maximum impact performance. However the highviscosity of such materials can create problems during processing, forexample with film blowing, such as high stresses and energy consumptionduring compounding and processing, degradation of the polymer,unbalanced machine direction and transverse direction tear strengths,and poor downgauging performance. This can make it difficult orimpossible to produce tough thin (10-15 micron) film. It is thereforenecessary to ensure that products suitable for film applications have amolecular weight distribution which lowers high shear (extrusion)viscosity while maintaining other desirable features. The copolymers ofthis aspect of the invention have rheology comparable to othercommercially available processable tough film grades (FIG. 2). Theviscosity-shear rate dependence shown graphically in FIG. 2 can bemodelled by the Carreau equation which extrapolates the curve tocalculate the zero shear rate viscosity. Thus the copolymer of Example32.5 has a rheology defined by the equationη=(4.455×10⁶)[1+1.776χ^(0.1286)]^(−(0.070/0.1286)) where η is viscosityat 180° C. and χ is the shear rate. The zero shear viscosity of thecopolymer of Example 32.5 is therefore intermediate between that of theother two commercial grades. Copolymers of this aspect of the inventionare preferred to have a zero shear viscosity of between 0.1×10⁶ Ps and12×10⁶ PS.

[0065] The polymers and copolymers of the invention are generally madein the form of a powder, the particle size of which may be from 0.1 to18 mm diameter. Pellets may also be made, having a diameter of 0.2 to 30mm.

[0066] The polymerisation conditions employed in the process of theinvention can be, for example, solution phase, slurry phase or gasphase. If desired, the catalyst can be used to polymerise the olefinunder high pressure/high temperature process conditions wherein thepolymeric material forms as a melt in supercritical ethylene. Preferablythe polymerisation is conducted under gas phase fluidised bedconditions. Suitable monomers for use in the polymerisation process ofthe present invention are, for example, ethylene, propylene, butene,hexene, methyl methacrylate, methyl acrylate, butyl acrylate,acrylonitrile, vinyl acetate, and styrene. Preferred monomers forhomopolymerisation processes are ethylene and propylene.

[0067] Slurry phase polymerisation conditions or gas phasepolymerisation conditions are particularly useful for the production ofhigh density grades of polyethylene. In these processes thepolymerisation conditions can be batch, continuous or semi-continuous.In the slurry phase process and the gas phase process, the catalyst isgenerally fed to the polymerisation zone in the form of a particulatesolid. In the case of catalyst (1) (and also catalyst (2) if this too isa compound according to formula B), this solid may be an undiluted solidcatalyst system formed from a nitrogen-containing complex and anactivator, or can be the solid complex alone. In the latter situation,the activator can be fed to the polymerisation zone, for example as asolution, separately from or together with the solid complex. Preferablythe catalyst system or the transition metal complex component of thecatalyst system employed in the slurry polymerisation and gas phasepolymeriastion is supported on a support material. Most preferably thecatalyst system is supported on a support material prior to itsintroduction into the polymerisation zone. Suitable support materialsare, for example, silica, alumina, zirconia, talc, kieselguhr, ormagnesia. Impregnation of the support material can be carried out byconventional techniques, for example, by forming a solution orsuspension of the catalyst components in a suitable diluent or solvent,and slurrying the support material therewith. The support material thusimpregnated with catalyst can then be separated from the diluent forexample, by filtration or evaporation techniques.

[0068] In the slurry phase polymerisation process the solid particles ofcatalyst, or supported catalyst, are fed to a polymerisation zone eitheras dry powder or as a slurry in the polymerisation diluent. Preferablythe particles are fed to a polymerisation zone as a suspension in thepolymerisation diluent. The polymerisation zone can be, for example, anautoclave or similar reaction vessel, or a continuous loop reactor, egof the type well-know in the manufacture of polyethylene by the PhillipsProcess. When the polymerisation process of the present invention iscarried out under slurry conditions the polymerisation is preferablycarried out at a temperature above 0° C., most preferably above 15° C.The polymerisation temperature is preferably maintained below thetemperature at which the polymer commences to soften or sinter in thepresence of the polymerisation diluent. If the temperature is allowed togo above the latter temperature, fouling of the reactor can occur.Adjustment of the polymerisation within these defined temperature rangescan provide a useful means of controlling the average molecular weightof the produced polymer. A further useful means of controlling themolecular weight is to conduct the polymerisation in the presence ofhydrogen gas which acts as chain transfer agent. Generally, the higherthe concentration of hydrogen employed, the lower the average molecularweight of the produced polymer.

[0069] The use of hydrogen gas as a means of controlling the averagemolecular weight of the polymer or copolymer applies generally to thepolymerisation process of the present invention. For example, hydrogencan be used to reduce the average molecular weight of polymers orcopolymers prepared using gas phase, slurry phase or solution phasepolymerisation conditions. The quantity of hydrogen gas to be employedto give the desired average molecular weight can be determined by simple“trial and error” polymerisation tests.

[0070] The polymerisation process of the present invention providespolymers and copolymers, especially ethylene polymers, at remarkablyhigh productivity (based on the amount of polymer or copolymer producedper unit weight of nitrogen containing transition metal complex employedin the catalyst system). This means that relatively very smallquantities of catalyst are consumed in commercial processes using theprocess of the present invention. It also means that when thepolymerisation process of the present invention is operated underpolymer recovery conditions that do not employ a catalyst separationstep, thus leaving the catalyst, or residues thereof, in the polymer (egas occurs in most commercial slurry and gas phase polymerisationprocesses), the amount catalyst in the produced polymer can be verysmall. Experiments carried out with the catalyst of the presentinvention show that, for example, polymerisation of ethylene underslurry polymerisation conditions can provide a particulate polyethyleneproduct containing catalyst so diluted by the produced polyethylene thatthe concentration of transition metal therein falls to, for example, 1ppm or less wherein “ppm” is defined as parts by weight of transitionmetal per million parts by weight of polymer. Thus polyethylene producedwithin a polymerisation reactor by the process of the present inventionmay contain catalyst diluted with the polyethylene to such an extentthat the transition metal content thereof is, for example, in the rangeof 1-0.0001 ppm, preferably 1-0.001 ppm. Using a catalyst comprising anitrogen-containing Fe complex in accordance with the present inventionin, for example, a slurry polymerisation, it is possible to obtainpolyethylene powder wherein the Fe concentration is, for example, 1.03to 0.11 parts by weight of Fe per million parts by weight ofpolyethylene.

[0071] Methods for operating gas phase polymerisation processes are wellknown in the art. Such methods generally involve agitating (e.g. bystirring, vibrating or fluidising) a bed of catalyst, or a bed of thetarget polymer (i.e. polymer having the same or similar physicalproperties to that which it is desired to make in the polymerisationprocess) containing a catalyst, and feeding thereto a stream of monomerat least partially in the gaseous phase, under conditions such that atleast part of the monomer polymerises in contact with the catalyst inthe bed. The bed is generally cooled by the addition of cool gas (egrecycled gaseous monomer) and/or volatile liquid (eg a volatile inerthydrocarbon, or gaseous monomer which has been condensed to form aliquid). The polymer produced in, and isolated from, gas phase processesforms directly a solid in the polymerisation zone and is free from, orsubstantially free from liquid. As is well known to those skilled in theart, if any liquid is allowed to enter the polymerisation zone of a gasphase polymerisation process the quantity of liquid is small in relationto the quantity of polymer present in the polymerisation zone. This isin contrast to “solution phase” processes wherein the polymer is formeddissolved in a solvent, and “slurry phase” processes wherein the polymerforms as a suspension in a liquid diluent.

[0072] The gas phase process can be operated under batch, semi-batch, orso-called “continuous” conditions. It is preferred to operate underconditions such that monomer is continuously recycled to an agitatedpolymerisation zone containing polymerisation catalyst, make-up monomerbeing provided to replace polymerised monomer, and continuously orintermittently withdrawing produced polymer from the polymerisation zoneat a rate comparable to the rate of formation of the polymer, freshcatalyst being added to the polymerisation zone to replace the catalystwithdrawn form the polymerisation zone with the produced polymer.

[0073] In the preferred embodiment of the gas phase polymerisationprocess of the present invention, the gas phase polymerisationconditions are preferably gas phase fluidised bed polymerisationconditions.

[0074] Methods for operating gas phase fluidised bed processes formaking polyethylene and ethylene copolymers are well known in the art.The process can be operated, for example, in a vertical cylindricalreactor equipped with a perforated distribution plate to support the bedand to distribute the incoming fluidising gas stream through the bed.The fluidising gas circulating through the bed serves to remove the heatof polymerisation from the bed and to supply monomer for polymerisationin the bed. Thus the fluidising gas generally comprises the monomer(s)normally together with some inert gas (e.g. nitrogen) and optionallywith hydrogen as molecular weight modifier. The hot fluidising gasemerging from the top of the bed is led optionally through a velocityreduction zone (this can be a cylindrical portion of the reactor havinga wider diameter) and, if desired, a cyclone and or filters todisentrain fine solid particles from the gas stream. The hot gas is thenled to a heat exchanger to remove at least part of the heat ofpolymerisation. Catalyst is preferably fed continuously or at regularintervals to the bed. At start up of the process, the bed comprisesfluidisable polymer which is preferably similar to the target polymer.Polymer is produced continuously within the bed by the polymerisation ofthe monomer(s). Preferably means are provided to discharge polymer fromthe bed continuously or at regular intervals to maintain the fluidisedbed at the desired height. The process is generally operated atrelatively low pressure, for example, at 10 to 50 bars, and attemperatures for example, between 50 and 120° C. The temperature of thebed is maintained below the sintering temperature of the fluidisedpolymer to avoid problems of agglomeration.

[0075] In the gas phase fluidised bed process for polymerisation ofolefins the heat evolved by the exothermic polymerisation reaction isnormally removed from the polymerisation zone (ie, the fluidised bed) bymeans of the fluidising gas stream as described above. The hot reactorgas emerging from the top of the bed is led through one or more heatexchangers wherein the gas is cooled. The cooled reactor gas, togetherwith any make-up gas, is then recycled to the base of the bed. In thegas phase fluidised bed polymerisation process of the present inventionit is desirable to provide additional cooling of the bed (and therebyimprove the space time yield of the process) by feeding a volatileliquid to the bed under conditions such that the liquid evaporates inthe bed thereby absorbing additional heat of polymerisation from the bedby the “latent heat of evaporation” effect. When the hot recycle gasfrom the bed enters the heat exchanger, the volatile liquid can condenseout. In one embodiment of the present invention the volatile liquid isseparated from the recycle gas and reintroduced separately into the bed.Thus, for example, the volatile liquid can be separated and sprayed intothe bed. In another embodiment of the present invention the volatileliquid is recycled to the bed with the recycle gas. Thus the volatileliquid can be condensed from the fluidising gas stream emerging from thereactor and can be recycled to the bed with recycle gas, or can beseparated from the recycle gas and sprayed back into the bed.

[0076] The method of condensing liquid in the recycle gas stream andreturning the mixture of gas and entrained liquid to the bed isdescribed in EP-A-0089691 and EP-A-0241947. It is preferred toreintroduce the condensed liquid into the bed separate from the recyclegas using the process described in our U.S. Pat. No. 5,541,270, theteaching of which is hereby incorporated into this specification.

[0077] When using the catalysts of the present invention under gas phasepolymerisation conditions, the catalyst, or one or more of thecomponents employed to form the catalyst can, for example, be introducedinto the polymerisation reaction zone in liquid form, for example, as asolution in an inert liquid diluent. Thus, for example, the transitionmetal component, or the activator component, or both of these componentscan be dissolved or slurried in a liquid diluent and fed to thepolymerisation zone. Under these circumstances it is preferred theliquid containing the component(s) is sprayed as fine droplets into thepolymerisation zone. The droplet diameter is preferably within the range1 to 1000 microns. EP-A-0593083, the teaching of which is herebyincorporated into this specification, discloses a process forintroducing a polymerisation catalyst into a gas phase polymerisation.The methods disclosed in EP-A-0593083 can be suitably employed in thepolymerisation process of the present invention if desired.

[0078] The present invention is illustrated in the following Examples.

EXAMPLES Example 9

[0079] 9.1 Preparation of 2.6-diacetylpyridinebis(2.4.6-trimethylanil)

[0080] To a solution of 2,6-diacetylpyridine (0.54 g; 3.31 mmol) inabsolute ethanol (20 ml) was added 2,4,6-trimethylaniline (1.23 g; 2.5eq.). After the addition of 2 drops of acetic acid (glacial) thesolution was refluxed overnight. Upon cooling to room temperature theproduct crystallised from ethanol. The product was filtered, washed withcold ethanol and dried in a vacuum oven (50° C.) overnight. The yieldwas 60% of theoretical. ¹H NMR(CDCl₃): 8.50, 7.95, 6.94, (m, 7H, ArH,pyrh), 2.33 (s, 6H, N═CCH₃), 2.28 (s, 6H, CCH₃), 2.05 (s, 12H, CCH₃).Mass spectrum: m/z 397 [M]⁺.

[0081] 9.2 Preparation of2.6-diacetylpyridinebis(2.4.6-trimethylanil)FeCl ₂

[0082] FeCl₂ (0.15 g; 1.18 mmol) was dissolved in hot n-butanol (20 ml)at 80° C. A suspension of2,6-diacetylpyridinebis(2,4,6-trimethylaniline(0.5 g; 1.18 mmol) inn-butanol was added dropwise at 80° C. The reaction mixture turned blue.After stirring at 80° C. for 15 minutes the reaction was allowed to cooldown to room temperature. The reaction volume was reduced to a few mland diethyl ether was added to precipitate the product as a blue powder,which was subsequently washed three times with 10 ml diethyl ether. Theyield was 64% of theoretical.

[0083] Mass spectrum: m/z 523 [M]⁺, 488 [M−Cl]⁺, 453 [M−Cl₂].

Example 27 Comparative

[0084] This Example shows polymerisation using a catalyst systemcontaining only a catalyst covered by the definition (1) in the presentinvention.

[0085] Preparation of the Supported Catalyst

[0086] 2,6-diacetylpyridinebis(2,4,6-trimethylanil)FeCl₂ was prepared asdescribed in Example 9. Silica (1.38 g ES70, supplied by Crosfield),which had been heated under flowing nitrogen at 700° C., was placed in aSchienk tube and toluene (10 ml) was added.

[0087] To a solution of2,6-diacetylpyridinebis(2,4,6-trimethylanil)FeCl₂ (0.041 g) in toluene(10 ml) was added methylaluminoxane (13.2 ml, 1.78M in toluene, suppliedby Witco). This mixture was heated at 40° C. for 30 minutes to dissolveas much of the iron complex as possible. The solution was thentransferred to the silica/toluene. The silica/MAO/toluene mixture wasmaintained at 40° C., with regular stirring, for 30 minutes before thetoluene was removed, at 40° C., under vacuum to yield a free flowingpowder. Analysis of the solid gave 16.9% w/w Al and 0.144% w/w Fe.

[0088] Polymerisation Tests

[0089] The reagents used in the polymerisation tests were: hydrogenGrade 6.0 (supplied by Air Products): ethylene Grade 3.5 (supplied byAir Products): hexene (supplied by Aldrich) distilled oversodium/nitrogen: dried pentane (supplied by Aldrich): methylaluminium(2M in hexanes, supplied by Aldrich): and triisobutylaluminium (1M inhexanes, supplied by Aldrich).

[0090] A 3 litre reactor was baked out under flowing nitrogen for atleast 1 hour at 77-85° C. before powdered sodium chloride (300 g,predried under vacuum, 160° C., >4 hours) was added. The sodium chloridewas used as a fluidisable/stirrable start-up charge powder for the gasphase polymerisation. Trimethyl aluminium (3 ml, 2M in hexanes) wasadded to the reactor and was boxed in nitrogen. The alkyl aluminium wasallowed to scavenge for poisons in the reactor for between ½-1 hourbefore being vented using 4×4 bar nitrogen purges. The gas phasecomposition to be used for the polymerisation was introduced into thereactor and preheated to 77° C. prior to injection of the catalystcomposition. The catalyst (0.18-0.22 g) was injected under nitrogen andthe temperature then adjusted to 80° C. The ratio of hexene and/orhydrogen to ethylene during the polymerisation was kept constant bymonitoring the gas phase composition by mass spectrometer and adjustingthe balance as required. The polymerisation tests were allowed tocontinue for between 1 to 2 hours before being terminated by purging thereactants from the reactor with nitrogen and reducing the temperature to<30° C. The produced polymer was washed with water to remove the sodiumchloride, then with acidified methanol (50 ml HCl/2.5L methanol) andfinally with water/ethanol (4:1 v/v). The polymer was dried undervacuum, at 40° C., for 16 hours. All the polymerisation tests werecarried out at a polymerisation temperature of 80° C. and at an ethylenepressure of 8 bars. The polymerisation conditions are set out in thefollowing Table. TABLE 1 Other cocatalyst Temp Ethylene H₂ hexene SCB/Ex. mmols ° C. barg barg barg 1000 C 27.3 TMA^(#)/6 80 8 0.5 0.2 0.127.7 — 80 8 — 0.86 1.6

[0091] These results show the relatively low level of comonomerincorporation when only a single Fe based catalyst is used; the higherlevel in Example 27.7 required a much greater amount of hexene to beadded.

Example 32

[0092] 32.1—Preparation of a Supported Ziegler Catalyst Component

[0093] Silica (20 kg), grade ES 70 supplied by Crosfield, which had beendried at 800° C. for 5 hours in flowing nitrogen, was slurried in hexane(110 litres) and hexamethyldisilazane (30 moles), supplied by Fluka, wasadded with stirring at 50° C. Dry hexane (120 litres) was added withstirring, the solid allowed to settle, the supernatant liquid removed bydecantation and further dry hexane (130 litres) was added with stirring.The hexane washing was repeated a further 3 times. Dibutylmagnesium (30moles), supplied by FMC, was added and stirred for 1 hour at 50° C.Tertiary butyl chloride (60 moles) was added and stirred for 1 hour at50° C. To this slurry was added an equimolar mixture of titaniumtetrachloride (3 moles), and titanium tetra-n-propoxide (3 moles) withstirring at 50° C. for 2 hours, followed by 5 washings with dry hexane(130 litres). The slurry was dried under a flowing nitrogen stream togive a solid, silica supported Ziegler catalyst component.

[0094] 32.2—Preparation of a Mixed Catalyst by Coimprepnation Containinga Ziegler Component and the Catalyst of Example 9

[0095] A solution of methylaluminoxane (“MAO”, 10.2 mmol) as a 10% wtsolution in toluene, supplied by Witco, was added to a suspension of2,6-diacetylpyridinebis(2,4,6-trimethylanil)FeCl₂ (0.07 mmol in 5 ml drytoluene), prepared as in Example 9, and the mixture shaken for 5minutes. This solution was then added to 2.0 g of the silica supportedZiegler catalyst prepared above (Example 32.1), the mixture shaken for 2hours at 20° C. and then the solvent removed under reduced pressure at20° C. to yield the mixed catalyst as a free flowing powder.

[0096] 32.3-32.4—Preparation of Mixed Catalysts by SequentialImpregnation Containing a Ziegler Component and the Catalyst of Example9

[0097] A sample of silica supported Ziegler catalyst (as prepared in32.1 above) was placed in a schlenk tube and toluene (5 ml) added toform a slurry. Methylaluminoxane, MAO (1.78M in toluene, supplied byWitco) was added to the schlenk and the resultant slurry shakenintermittently at room temperature for 30 minutes. The supernatantliquid was removed and the solid washed with toluene (10 ml) at roomtemperature. The volatile components of the resultant solid were thenremoved under reduced pressure at 20° C. to yield a solid free flowingpowder.

[0098] (2,6-diacetylpyridinebis(2,4,6 trimethyl anil) iron dichloride(prepared as described in Example 9 above) was added to a slurry of theabove powder in toluene (Omi) at room temperature for 1 hour. Themixture was occasionally shaken then the supernatant was removed bydecantation and the resulting solid was dried under vacuum at 20° C.

[0099] Two catalysts were made by this method, with the amounts of eachcatalyst component (“Ziegler” and “Fe”) and MAO used given below: Fe MAOZiegler/MAO Ziegler/MAO/Fe Catalyst Ziegler g mmol mmol washing(toluene) washing (hexane) 32.3 2 0.070 10.45 1 × 10 ml 2 × 5 ml 32.4 20.073 3.56 1 × 10 ml 2 × 5 ml

[0100] 32.5-32.18—Polymerisation of Ethylene/Hexene Mixture Using aMixed Catalyst

[0101] A 3 litre reactor equipped with a helical stirrer was heated to77-95° C. for 1 hour with dry nitrogen flowing through. Dry sodiumchloride (300 g) was then added with trimethylaluminium (IMA) solution(2 ml of 2 molar TMA in hexane) and the reactor heated at 85° C. for0.5-1 hours. The reactor was purged with nitrogen, cooled to 50° C. andTMA solution (3 ml of 2 molar TMA in hexane) added. The temperature wasraised to 77° C. and hydrogen (0.5 bar) and ethylene (8 bar) added priorto the addition of 1-hexene (2.6 ml). Reaction was started by injectioninto the reactor of one of the mixed catalysts 32.2, 32.3 or 32.4(0.1-0.3 g) prepared above. The temperature was maintained at 80° C. andethylene added to maintain constant pressure. The gas phase wasmonitored by a mass spectrometer and hydrogen and 1-hexene added asnecessary to maintain constant gas phase concentrations of thesecomponents. The polymerisation was carried out for 60 minutes. Thepolymer was washed with water to remove the sodium chloride, then withacidified methanol (50 ml HCV2.5 litres methanol) and finally withwater/ethanol (4:1 v/v). The polymer was dried under vacuum, at 40° C.for 16 hours.

[0102] Details of the reactions are given in Table 2 below. For Examples32.3 to 32.8, 32.10, 32.11 and 32.13, R=0.025 and 18.18R−0.16=0.29. ForExample 32.9, R=0.050 and 18.18R−0.16=0.75. For Example 32.12, R 0.038and 18.18R−0.16=0.51. TABLE 2 Gas phase Catalyst Catalyst co-catalyst/Temp Ethylene H₂ 1-hexene Polymer SCB/ Ex. used Injected g mmols ° C.barg barg barg Yield g 1000 C 32.5 32.3 0.19 TMA^(#)/20 80 8 0.08 0.2 685.7 32.6 32.3 0.19 TMA^(#)/6 80 8 0.09 0.2 161 1.4 32.7 32.3 0.18TMA^(#)/20 80 8 0.5 0.2 55 3.7 32.8 32.3 0.18 TMA^(#)/6 95 8 0.5 0.2 1562.6 32.9 32.3 0.19 TEA*/6 80 8 0.5 0.2 143 0.4 32.10 32.3 0.18TMA^(#)/12 80 8 0.5 0.2 66 2.5 32.11 32.3 0.10 TMA^(#)/6 80 8 0.5 0.4 596.6 32.12 32.3 0.19 TMA^(#)/6 80 8 0.5 0.2 123 1.8 32.13 32.3 0.12TMA^(#)/6 65 8 0.28 0.2 84 32.14 32.3 0.10 TMA^(#)/6 80 14 0.17 0.3 18532.15 32.4 0.12 TMA^(#)/6 80 8 0.5 0.2 82 32.16 32.2 0.20 TMA^(#)/6 80 80.5 0.2 111 2.3 32.17 32.2 0.21 TMA^(#)/6 80 8 3 0.2 55 3.5 32.18 32.20.20 TMA^(#)/6 80 8 0.06 0.2 76 3.2

[0103] The above table shows clearly that much higher levels ofcomonomer incorporation are achieved at relatively low levels ofcomonomer concentration by the used of the mixed catalyst system of theinvention (compare Example 27.3, which also has a hexene partialpressure of 0.2 bar but an SCB of only 0.1/1000C). The comonomerincorporation is also concentrated in the high molecular weight part ofthe copolymer.

[0104] Physical Properties of Product of Example 32.5

[0105] Modulus Measurement

[0106] Modulus test samples were compression moulded to a thickness ofapproximately 200 mm using a Moores hydraulic press. A picture framemould was prepared by cutting a 25 cm square in a sheet of aluminiumfoil and sandwiching this frame between two sheets of melinex, aluminiumsheet, and steel plates. 3 g of polymer was evenly arranged in thepicture frame mould, which was then assembled and transferred to thepress (pre-heated to 200° C.). The plattens were then closed to acontact pressure of 10 kg/cm² and held for 3 minutes after which fullpressure (20 tons) was applied for 5 minutes. The press was then crashcooled with cold water running through the plattens with the pressureheld at 20 tons. Once cool the pressure was released, moulddisassembled, and the flash trimmed from the polymer sheet. For modulusmeasurement parallel sided specimens of dimensions 100 mm×5 mm were cutfrom each sheet and the exact dimensions accurately measured.

[0107] Samples were tested in an Instron using a 100N load cell at astrain rate of 2 mm/min. Samples were gripped with a pneumatic grip atthe bottom and a manual screw grip at the the top so that the guagelength (ungripped section) of the sample was 20 mm. The 1% secantmodulus was calculated over the initial (1% strain) linear section ofthe stress-strain curve. Typically six specimens were tested and theresults averaged.

[0108] The product of Example 32.5 was found to have a secant modulus of529 MPa. It had an SCB of 5.7/1000C. This values are plotted in FIG. 1(the single point above the diagonal line), together with pointscorresponding to commercially available copolymers outside the scope ofthe invention.

[0109] The polymer of Example 32.5 had a broad molecular weightdistribution (as determined by gel permeation chromatography. Thepolydispersity (Mw/Mn) was 28.5.

[0110] Dynamic Shear Rheometry Measurement

[0111] 2 g of polymer sample (containing 0.2% Irganox 1010 antioxidantif uncompounded reactor powder used) was weighed out and distributedevenly around a steel mould shaped in form of disks 25 mm diameter and 2mm in thickness. This mould was sandwiched between steel plates andplaced in a press pre-heated to 190° C. The sample was exposed firstlyto low pressure (10 kg/cm²) for 3 mins then high pressure (20 tons) for5 mins, after which the press plattens were rapidly cooled via a supplyof cold water. Once the plattens had reached room temperature thepressure was released and sample removed. Excess polymer flashing wasremoved prior to loading into the rheometer.

[0112] Sample rheology was measured with a Rheometrics RDS2 dynamic,strain-controlled rheometer at 180° C. using a strain of 5%, parallelplate geometry (25 mm diameter plates), over a frequency range of0.01-100 rad/s.

[0113] A plot showing the complex viscosity of Example 32.3 comparedwith two commercial HDPE tough film grades is shown in FIG. 2; thisdemonstrates that the copolymer has acceptable Theological propertiesfor commercial use.

[0114] Holtrop Analysis of the Polymer Produced in Example 32.5

[0115] Mixtures of 2-n-butoxyethanol, xylene and Irganox 1010Ffat (0.15g) were premeasured into round bottom flasks. Fraction 1 (see Table 3abelow) was placed in a cruicible and heated to 120-122° C. A sample ofpolymer (5 g) was ground using a Reich mill (1 mm mesh) and added to thepre-heated solvent mixture. The polymer slurry was stirred 60 rpm for 20minutes after which the liquid components of the mixture were drainedthrough a microfilter, cooled and mixed with acetone (500 min) in orderto precipitate the dissolved polymer. The next solvent fraction was thenadded to the crucible and the procedure repeated in order for all thesolvent ratios shown below. The isolated polymers were dried for 6 hoursin a vacuum oven at 40° C. prior to analysis. TABLE 3a Non-solventSolvent FRACTION 2-n-butoxyethanol (ml) Xylene (ml) TOTAL (ml) 1 186 114300 2 174 126 300 3 162 138 300 4 156 144 300 5 150 150 300 6 146 154300 7 142 158 300 8 138 162 300 9  0 300 300 1254  1446  2700 

[0116] TABLE 3b Mw Mn SCB/1000 C SCB/1000 C Fraction (× 10³) (× 10³)Mw/Mn IR ¹H NMR Bulk 304 20 15 6.5 5.8 1 8.3 2.21 3.76 1.3 3.8 2 21.36.16 3.46 5.9 4.9 3 41.5 13.2 3.14 6.3 4 79.1 31.6 2.5 9 6.8 5 121.432.2 3.77 7.8 6 109.2 38.9 2.81 7.2 7 132.1 46.2 2.86 6.3 8 318 36.4 4.89 582.3 127.6 4.56 3.3

[0117] These results show that for a product derived from a multisitecatalyst and being at the very earliest experimental stage (andtherefore non-optimised), comonomer can be preferentially incorporatedin a fraction of the copolymer with respect to product molecular weight.

Example 41

[0118] Example shows the use of a combination of a metallocene-typecatalyst with a catalyst based on an iron complex of the presentinvention for polymerising ethylene under slurry conditions.

[0119] 41.1—Preparation of a Supported Metallocene Catalyst

[0120] To silica (Crosfield grade ES70, previously calcined at 200° C.in flowing N₂ for 5 hrs) was added a toluene solution ofmethylaluminoxane (MAO) containing dissolvedbis(n-butylcyclopentadienyl)ZrCl₂. The amounts used were 2.5 mmol MAOper gram of silica and 0.05 mmol metallocene per gram silica. Theresulting slurry was stirred gently for at least 1 hour before beingdried under reduced pressure to give a free flowing powder.

[0121] 41.2—Preparation of the Combined Metallocene/Fe-Complex Catalyst

[0122] The supported metallocene catalyst (2.5 g) prepared as describedin step 41.1 above was placed in a Schlenk tube and a slurry of2,6-diacetylpyfidinebis(2,4,6 trimethyl anil) iron dichloride (73 mg) inhexane (10 mi) was added thereto at ambient temperature. The mixture washeated to 80° C. and left for 90 minutes with occasional shaking tomaintain a well-mixed solution. There was no colouration evident in thesupernatant solution above the solid. The produced catalyst was dried at80° C. under vacuum to leave a dry free flowing powder.

[0123] 41.3—Polymerisation of Ethylene

[0124] A 1 litre reactor was heated under flowing nitrogen for 1 hour at80° C. before being cooled to 30° C. Triisobutyl aluminium (3 ml of 1Min hexanes) was added to the reactor followed by 500 ml of isobutane.The reactor was heated to 77° C. and the pressure increased to 12.9 bar.Ethylene was added to give 20.9 bar total pressure. The catalyst (0.100g, slurried in hexane) prepared as described in 41.2 above was injectedinto the reactor. The ethylene pressure during the polymerisation wasestimated to be approximately 8 bar. Polymerisation was allowed tocontinue for 60 minutes. 96 g of polymer was recovered. Analysis of thepolymer by GPC indicated Mw and Mn to be 471000 and 30000 respectively.

Comparative Test 41.4

[0125] This shows the polymerisation of ethylene using only thesupported metallocene catalyst described in step 41.1.

[0126] A 1 litre reactor was heated under flowing nitrogen for 1 hour at80° C. before being cooled to 30° C. Triisobutyl aluminium (3 ml of 1Min hexanes) was added to the reactor followed by 500 ml of isobutane.The reactor was heated to 75° C. and the pressure increased to 12.7 bar.Ethylene was added to give 20.7 bar total pressure. The supportedmetallocene catalyst (0.094 g, slurried in hexane) prepared in step 41.1above was injected into the reactor. The ethylene pressure during thepolymerisation was estimated to be approximately 8 bar. Polymerisationwas allowed to continue for 60 minutes. 49 g of polymer was recovered.Analysis of the polymer by GPC indicated Mw and Mn to be 142000 and53000 respectively.

Example 42

[0127] This Example shows the use of a combination of a Phillipscatalyst with a catalyst based on an iron complex of the presentinvention for polymerising ethylene under slurry conditions.

[0128] 42.1 Preparation of Phillips Catalyst

[0129] To HA30WFL Phillips Cr on silica catalyst (Supplied by Grace,activated in flowing air for 5 hrs at 550° C., 295.1 g) was added atoluene solution of MAO (Witco, 515 ml×1.47 M, 0.76 mol). The additiontook 30 minutes during which time the flask was gently swirled to ensurean even coating and the orange Cr catalyst turned chocolate brown. Theslurry was placed in a waterbath at 50° C. for 1 hr and was shakenperiodically to thoroughly mix. The solvent was then removed by vacuumat 50° C. until fluidisation of the catalyst had stopped, leaving a freeflowing khaki-green powder. Yield=347.7 g. Analysis by ICP 5.96w/w % Aland 0.85w/w % Cr.

[0130] 42.2 Preparation of MixedPhillips/2,6-diacetylpyridinebis(2.4.6-trimethylanil)FeCl₂ Catalyst

[0131] To the MAO treated Phillips catalyst of Example 42.1 (2.7 g)slurried in anhydrous hexane (10 ml) was added a slurry of2,6-diacetylpyridinebis(2,4,6 trimethyl anil) iron dichloride fromExample 9.2 (36 mg, 6.9×10⁻² mmol) in anhydrous hexane (10 ml). Theresulting slurry was vigorously shaken for 10 mins, the solid allowed tosettle and the colourless supernatant decanted. The remaining solid waswashed with hot hexane (2×15 ml), decanted and pumped dry under vacuumat 50° C. until fluidisation of the solid had stopped yielding agreen/brown free flowing powder. Iron loading calculated to be 0.14%w/w.

[0132] 42.3—Polymerisation of Ethylene

[0133] A 1L reactor was heated under flowing nitrogen for 1 hour at 90°C. before being cooled to 30° C. Triisobutyl aluminium (3 ml×1M inhexanes) followed by isobutane (500 mi) was added to the reactor. Thereactor was sealed and heated to 80° C. raising the pressure to 13.9bar. Ethylene was added to give 26.9 bar total pressure, the vessel wasagain sealed and cooled to 78° C. The catalyst of Example 42.2 (0.099 g,slurried in 5 cm³ hexane) was injected into the reactor raising thepressure by 0.3 bar. The reactor pressure was controlled at 27.2 barduring the test (ethylene pressure estimated to be approximately 13.0bar) and the temperature adjusted to 80° C. Polymerisation was allowedto continue for 120 minutes. 76.1 g of polymer was recovered. Analysisof the polymer by GPC indicated Mw and Mn to be 722000 and 15000respectively (polydispersity=48.0).

Example 45

[0134] This Example shows the preparation of a further mixed catalystcomprising a Ziegler catalyst and the catalyst prepared in Example 9above. The polymer made using this catalyst was blown into a film.

[0135] Pre-Impregnation of Support with Activator Compound

[0136] All the following operations were conducted under a nitrogenatmosphere unless stated. A sample of silica supported Ziegler catalystwas placed in a schienk tube and toluene added to form a slurry.Methylaluminoxane, MAO (1.78M in toluene, supplied by Witco) was addedto the schlenk tube and the resultant slurry mixed intermittently atroom temperature. The supernatant liquid above the solid was removed andthe solid washed with toluene at room temperature. The volatilecomponents of the resultant material were then removed under reducedpressure at 20° C. to yield the solid as a free flowing powder. Fourdifferent supports were prepared, listed in Table 4 below. TABLE 4Silica Toluene in Reaction Toluene Ex- supported MAO MAO:Ti slurry timewash ample Ziegler g mmol ratio cm³ mins cm³ 45.1 20 104 25:1  50 30 10045.2 50 261 25:1 125 30 125 45.3 80 418 25:1 100 60 100 45.4 80 167 . .. 300 30 200

[0137] Supporting the Catalyst

[0138] 2,6-diacetylpyridinebis(2,4,6 trimethyl anil) iron dichlorideprepared as described in Example 9 above was added to a slurry of eachof the four the solid supports in toluene at room temperature. Themixture was occasionally shaken, the supernatant solution removed, andthe supported catalyst washed with toluene followed by a mixture ofhexanes (hexane 40-60° C., supplied by Aldrich). The solid was driedunder vacuum at 20° C. Table 5 below shows the preparative details forthe four catalysts thus prepared. TABLE 5 Toluene Re- Sup- in actionToluene Hexane Ex- port Fe MAO:Fe slurry time wash wash ample g mmolratio cm³ mins cm³ cm³ 45.1 26 0.70 150:1   100 45 0 100 45.2 30 0.70100:1** 100 45 0 100 45.3 105 2.79 150:1   400 30 400 400 45.4 90 1.11150:1   220 30 150 140

[0139] Preparation of Mixed Catalysts by Coimpregnation Containing aZiegler Component and the Catalyst of Example 9

[0140] All the following operations were conducted under a nitrogenatmosphere unless stated. A solution of methylaluminoxane as a 10% wtsolution in toluene, supplied by Witco, was added to a suspension of2,6-diacetylpyridinebis(2,4,6-trimethylanil)FeCl₂, prepared as inExample 9, and the mixture shaken. This solution was then added to thesilica supported Ziegler catalyst prepared above (Example 32.1) and theresultant slurry mixed intermittently at room temperature. The volatilecomponents of the resultant material were then removed under reducedpressure at 20° C. to yield the mixed catalyst as a free flowing powder.The supported catalysts prepared, are listed below. Silica TolueneReaction Supported MAO Fe in slurry time Example Ziegler g mmol mmolMAO:Ti:Fe cm³ mins 45.5 200 348 8.40 41:5:1 400 30 45.6 100 139 1.6883:12:1 200 30

[0141] Polymerisation

[0142] The six catalysts prepared above were used to polymeriseethylene. The polymerisation was conducted in a continuous fluidised bedreactor of 15 cm diameter.

[0143] Ethylene, n-hexene, hydrogen and TEARED were fed into thereactor: starting with a seed-bed of polyethylene powder (approx. 1000g), catalyst was injected into the reactor and the polymerisationcarried out to increase the mass of the bed to approximately 3.5 kg.Polymerisation and product withdrawal was continued to yield a productsubstantially free of the starting bed. Process conditions for each ofthe polymerisations conducted are given in Table 6 below. TABLE 6 Ti SiAluminium Ethylene Hexene Al residue residue residue Example Alkyl H₂[bar] [bar] [bar] ppm ppm ppm 45.1 TEA 0.46 8 0.18 93 4.4 180 45.2a TEA0.23 4 0.09 94 4.9 160 45.2b TEA 0.16 4 0.09 72 6 222 45.3 TEA 0.17 40.09 175 4.2 160 45.4 TEA 0.17 4 0.09 146 6.7 193 45.5a TMA 0.26 4 0.20208 6.2 152 45.5b TMA 1.68 8 0.00 174 7.5 216 45.6 TEA 0.49 4 0.2 1859.9 285

[0144] Properties of the polymers obtained for the above polymerisationsare given in Table 7 below, with additional data for Examples 45.5a and45.5b in Table 8. TABLE 7 Average Example HLMI HLMI Density kg/m³ Mn MwMw/Mn Bu/1000 C 45.1  3.5 3.5 945 — — — 1.6 45.2a 5.2-4.2 4.5 952 15000268000 18.4 0.7 45.2b 3.3-3.8 4 951 19000 278000 14.4 45.3 2.98-3.7  3951 19000 241000 12.4 45.4 3.38-4   3.5 948 27000 245000 9.2 45.5a 10.510.5 951 23000 165000 7.1 45.5b 10.5 10.5 957 22000 234000 10.8 45.611.5 11.5 950 26000 168000 6.4

[0145] TABLE 8 Average PE Yield Particle % Fines Example KgPE/gCatalystSize (μm) (<125 μm) Span 45.5a 2.2 458 2.6 1.3 45.5b 1.6 350 8.2 1.6

[0146] Compounding

[0147] The polymers in Table 6 were compounded: the powder extractedfrom the polymerisation reactor was stabilised with 1000 ppm of processantioxidant Irgafos PEPQ, 1000 ppm of a long term antioxidant Irganox1010 and 1000 ppm of a neutralizer (calcium stearate). The blend ofpowder and additives was compounded in a twin screw extruder type Werner53 equipped with two 53 mm diameter screws with a length/diameter ratioof 48. The temperature profile along the screw was between 220° C. and240° C.

[0148] Film Blowing

[0149] The compounded polymers 45.1 to 45.4 were then extruded on anAXON BX¹⁸ type extruder with a die diameter of 70 mm, and a die gap of 1mm. The screw diameter was 18 mm with a LID ratio of 30. Details of theextrusion conditions are given in Table 9 below, together with the FilmAppearance Rating (FAR), which is a measurement of the gels andfish-eyes content in each film sample. TABLE 9 Example 45.1 45.2a 45.2b45.3 45.4 Temp profile (° C.) 190-230 190-230 190-130 190-230 190-230Screw speed (revs/min) 154 148 196 170 150 Melt pressure (bar) 428 468495 497 488 Melt temp (° C.) 221 222 223 229 226 Output (kg/hr) 1.5 1.92.0 2.2 2.0 Take off speed (m/min) 2.1 2.5 3.0 2.5 2.5 Blow Up Ratio 2:12:1 2-3:1 2:1 2:1 Frostline (mm) min* min min min min Motor load (Amps)3.10 3.06 3.0 2.97 3.19 Film thickness (μm) 12.32 22.30 18-26 25-3222-26 FAR −40 −40 −20 −30 −20

[0150] The compounded polymers 45.5a, 45.5b and 45.6 were extruded on aCollin type extruder with a die diameter of 70 mm, and a die gap of 0.8mm. Details of the extrusion conditions are given in Table 10 below,together with the Film Appearance Rating (FAR). TABLE 10 Example 45.5a45.5b 45.6 Screw speed (revs/min) 38 38 37 Melt pressure (bar) 460 430417 Melt temp (° C.) 181 177 180 Output (kg/hr) 9 9 9 Take off speed(m/min) 14.4 14.4 14.2 Blow Up Ratio 3:1 3:1 3:1 Motor load (Amps) 16.915.5 15.6 Film thickness (μm) 17-22 16-20 14-22 FAR +20 +20 +20

[0151] These results show that for a product derived from a multisitecatalyst and being at the very earliest experimental stage (andtherefore non-optimised), the optical properties are surprisingly good.The relatively good film appearance rating FAR indicates that there areunexpectedly low gel levels in the film.

1. Polymerisation catalyst comprising (1) a compound of the Formula B:

wherein M is Fe[II], Fe[III], Co[I], Co[II], Co[III], Mn[I], Mn[II],Mn[m], Mn[IV], Ru[II], Ru[III] or Ru[IV]; X represents an atom or groupcovalently or ionically bonded to the transition metal M; T is theoxidation state of the transition metal M and b is the valency of theatom or group X; R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are independentlyselected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl; and when any two ormore of R¹-R⁷ are hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl, said two or more canbe linked to form one or more cyclic substituents; and (2) a furthercatalyst.
 2. Catalyst according to claim 1 wherein compound (1) has thefollowing Formula

wherein M is Fe[II], Fe[III], Co[I], Co[II], Co[III], Mn[I], Mn[II],Mn[III], Mn[IV], Ru[II], Ru[III] or Ru[IV]; X represents an atom orgroup covalently or ionically bonded to the transition metal M; T is theoxidation state of the transition metal M and b is the valency of theatom or group X; R¹ to R⁴, R⁶ and R¹⁹ to R²′ are independently selectedfrom hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl; when any two or moreof R¹ to R⁴, R⁶ and R¹⁹ to R²⁸ are hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl, said two or more canbe linked to form one or more cyclic substituents; with the proviso thatat least one of R¹⁹, R²⁰, R²¹ and R²² is hydrocarbyl, substitutedhydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl whenneither of the ring systems P and Q forms part of a polyaromaticfused-ring system.
 3. Catalyst according to claim 2 wherein neither ofthe ring systems P and Q forms part of a polyaromatic ring system, andwherein at least one of R¹⁹ and R²⁰, and at least one of R²¹ and R²² isselected from hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl orsubstituted heterohydrocarbyl.
 4. Catalyst according to claim 2 whereinneither of the ring systems P and Q forms part of a polyaromaticfused-ring system and wherein each of R¹⁹, R²⁰, R²¹ and R²² is selectedfrom hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl orsubstituted heterohydrocarbyl.
 5. Catalyst according to claim 1 whereinthe Formula B compound has the following Formula T

and wherein M is Fe[II], Fe[III], Co[I], Co[II], Co[III], Mn[I], Mn[II],Mn[III], Mn[IV], Ru[II], Ru[III] or Ru[IV]; X represents an atom orgroup covalently or ionically bonded to the transition metal M; T is theoxidation state of the transition metal M and b is the valency of theatom or group X; R¹ to R⁴, R⁶ and R²⁹ to R³² are independently selectedfrom hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl; when any two or moreof R¹ to R⁴, RE and R² to R³² are hydrocarbyl, substituted hydrocarbyl,heterohydrocarbyl or substituted heterohydrocarbyl, said two or more canbe linked to form one or more cyclic substituents.
 6. Catalyst accordingto any preceding claim wherein X is selected from halide, sulphate,nitrate, thiolate, thiocarboxylate, BF⁴ ⁻, PF₆ ⁻, hydride,hydrocarbyloxide, carboxylate, hydrocarbyl, substituted hydrocarbyl andheterohydrocarbyl.
 7. Catalyst according to claim 6 wherein X isselected from chloride, bromide, iodide, methyl, ethyl, propyl, butyl,octyl, decyl, phenyl, benzyl, methoxide, ethoxide, isopropoxide,tosylate, triflate, formate, acetate, phenoxide and benzoate. 8.Catalyst according to any preceding claim wherein catalyst (2) comprisesa Ziegler Natta catalyst, a Phillips type (chromium oxide) catalyst, ametallocene catalyst, a monocyclopentadienyl constrained geometry typecatalyst or a bidentate α-diimine late transition metal catalyst. 9.Catalyst according to claim 8 wherein the further catalyst (2) comprisesa heterogeneous catalyst or a supported catalyst which provides asupport for compound (1).
 10. Catalyst according to any of claims 1 to 7wherein compounds (1) and (2) are each independently a transition metalcompound of Formula B.
 11. Catalyst according to any preceding claimwhich additionally comprises (3) an activating quantity of an activatorcompound comprising a Lewis acid capable of activating the catalyst forolefin polymerisation.
 12. Catalyst according to claim 11 wherein theactivating compound comprises an organoaluminium compound or ahydrocarbylboron compound.
 13. Process of making a catalyst as definedin claim 11 or 12 wherein catalyst (2) is a Ziegler-Natta catalyst, andcomponents (1) and (3) are premixed prior to addition to (2). 14.Catalyst according to any preceding claim which additionally comprises(4) a neutral Lewis base.
 15. Process for the polymerisation orcopolymerisation of 1-olefins, comprising contacting the monomericolefin(s) under polymerisation conditions with a polymerisation catalystas defined in any preceding claim.
 16. Process according to claim 15wherein the polymerisation is conducted in the presence of hydrogen as amolecular weight modifier.
 17. Process according to claim 15 or 16wherein the polymerisation conditions are solution phase, slurry phaseor gas phase.
 18. Process according to claim 17 wherein thepolymerisation is conducted under gas phase fluidised bed conditions.19. Process according to claim 17 wherein the polymerisation isconducted in slurry phase in an autoclave or continuous loop reactor.20. Process according to any one of claims 15 to 19 which comprises thecopolymerisation of ethylene and a further 1-olefin, wherein the degreeof short chain branching per thousand carbons (SCB) in the resultantcopolymer is greater than zero and also equal to or greater than18.18R−0.16 where R is the ratio of partial pressure of the further1-olefin to that of ethylene.
 21. Process according to claim 20 whereinthe SCB is greater than or equal to 18.18R−0.05, preferably 18.18R−0.04.22. Copolymer of ethylene and a further 1-olefin having an SCB of 2.0,preferably 3.0 or greater and comprising residues of anitrogen-containing iron complex, wherein the iron concentration is from0.01 to 1000 parts by weight per million parts of copolymer, preferably0.01 to 10 ppm by weight, for example 0.11 to 1.03 ppm by weight. 23.Method of selecting the portion of the molecular weight distribution ofa copolymer of ethylene and a further 1-olefin in which units of saidfurther 1-olefin are located, comprising contacting the monomericolefins under polymerisation conditions with a polymerisation catalystas defined in any one of claims 1 to
 13. 24. Copolymer of ethylene and afurther 1-olefin which contains residues of a nitrogen-containing ironcomplex wherein the iron concentration is from 0.01 to 10 parts byweight per million parts of copolymer, and in which at least 50% of theshort chain branching is located in the 50% by weight of the copolymerhaving the highest molecular weight.
 25. Copolymer of ethylene and afurther 1-olefin wherein the degree of short chain branching perthousand carbons (SCB) is from 2.0 to 10, and the relationship ofmodulus in MPa (M) to SCB (B) is defined by the equation M=k−62.5B wherek is 820 or greater.
 26. Copolymer according to claim 25 wherein the SCBis between 2 and
 8. 27. Copolymer according to claim 25 wherein the SCBis greater than 2.5, preferably greater than 3.0.
 28. Copolymeraccording to one of claims 25 to 27 wherein k is 830 or greater,preferably 840 or greater, more preferably 850 or greater.
 29. Copolymeraccording to one of claims 25 to 27 wherein M=k−65.5B where k is 850 orgreater, preferably M=k−67.5B where k is 870 or greater, and morepreferably M=k−70.5B where k is 90° or greater.
 30. Copolymer accordingto one of claims 25 to 27 wherein M=k−60B where k is 815 or greater,preferably M=k−57.5B where k is 810 or greater, and more preferablyM=k−55B where k is 805 or greater.